Q. The liquid in my tumbler doesn’t stay hot or cold for very long. What could be the reason?

If your tumbler is not maintaining temperature effectively, the vacuum seal may be damaged.
Signs of this include condensation forming on the exterior when using cold liquids or the exterior heating up with hot liquids.
Damage to the vacuum seal can occur if the tumbler has been dented by an impact, such as being dropped.
Unfortunately, once the vacuum seal is compromised, it cannot be repaired.